1. Field of the Invention
The present invention relates to a transfer film, a method for producing a transfer film, a transparent laminate, a method for producing a transparent laminate, a capacitance-type input device, and an image display device. More particularly, the invention relates to a capacitance-type input device that is capable of detecting the position of contact of a finger as a change in the capacitance, a transparent laminate that can be used for the capacitance-type input device, a transfer film that is used to produce a transparent laminate, a method for producing a transfer film, a method for producing a transparent laminate using this transfer film, and an image display device comprising this capacitance-type input device as a constituent element.
2. Description of the Related Art
In recent years, in regard to electronic equipment such as mobile telephones, car navigation systems, personal computers, ticket-vending machines, and automatic teller machines, a tablet-type input device is disposed on the surface of a liquid crystal device or the like, so that when a finger, a touch pen or the like touches the site of an instruction image displayed on an image display region of the liquid crystal device while this indication image is referred to, input of the information coping with the instruction image can be achieved.
Examples of such an input device (touch panel) include resistive film-type devices and capacitance-type devices. However, since a resistive film-type input device has a two-ply structure composed of a film and a glass plate, in which a short circuit is caused by pressing down the film, such a resistive film-type input device has a defect that the operation temperature range thereof is narrow, and the device is not quite resistant to changes over time.
In contrast, a capacitance-type input device is advantageous in that simply a light-transmitting conductive film may be formed on a single sheet of substrate. In regard to such a capacitance-type input device, for example, there is available an input device of a type in which electrode patterns are extended in directions that intersect each other, so that when a finger or the like touches the device, any change in capacitance between the electrodes is sensed, and the position of input is detected (see, for example, JP2010-86684A, JP2010-152809A, and JP2010-257492A).
In a case of using such a capacitance-type input device, for example, there has been a problem of visibility, such as that a transparent electrode pattern is visually recognized at a position slightly away from the vicinity of a position where regular reflection occurs when the device is lighted by a light source, and the appearance becomes poor. In this regard, JP2010-86684A describes that when an ITO (Indium Tin Oxide) pattern is formed on a substrate, and a layer formed from a low-refractive index dielectric material such as SiO2 and a layer formed from a high-refractive index dielectric material such as Nb2O5 are alternately laminated only on the upper side of the ITO pattern, the transparent electrode pattern becomes stealthy due to the optical interference effect provided by those various layers, and neutral color tones are obtained.
JP2010-152809A describes that if, before an ITO pattern is formed on a substrate, a low-refractive index layer of SiO2 or the like and a high-refractive index layer of Nb2O5 or the like are laminated only on the lower side of the ITO pattern, and then the ITO pattern is formed, the shape of the transparent electrode pattern can be prevented from appearing.
JP2010-257492A describes that if, before an ITO pattern is formed on a substrate, a low-refractive index layer of SiO2 or the like and a high-refractive index layer of Nb2O5 or the like are laminated only on the lower side of the ITO pattern, and then the ITO pattern is formed, the transparent electrode pattern or the intersections between patterns can be made unnoticeable.
Regarding the method for forming a transparent film such as a transparent insulating layer or a transparent protective film as described in these patent documents, various methods are known. Here, among smartphones or tablet computers comprising a capacitance-type touch panel on a liquid crystal display or an organic EL display, devices that use reinforced glass, which is represented by GORILLA GLASS of Corning, Inc., for the front face plate (surface that is brought into direct contact with the finger) have been developed and publicized. Also, devices in which an opening for installing a pressure-sensitive (mechanical mechanism not based on capacitance change but based on pressing force) switch is formed in a portion of the front face plate, have been marketed. Since such reinforced glass has high strength and is not easily processable, in order to form an opening, it is common to form an opening before a reinforcement treatment, and then to perform the reinforcement treatment.
In WO 2010-061744A and JP2010-061425A, as a method for forming a transparent insulating layer or a transparent protective film, in a case in which an organic material is used, only methods of performing coating are described. However, when it is attempted to form a transparent insulating layer or a transparent protective film using the materials described in JP2010-257492A or WO 2010-061744A according to the coating method described in WO 2010-061744A or JP2010-061425A on a reinforcement-treated substrate having an opening as described above, leakage or extrusion of resist components through the opening occurs, and a process for removing the extruded portion is needed. Thus, there is a problem that the production efficiency is markedly decreased.
On the other hand, JP2007-334045A and JP2008-107779A describe transfer materials for color filters, and it has been suggested to laminate such a transfer material on a substrate. In these documents, however, even though utilization of the transfer materials in liquid crystal display devices is mentioned, improvement of the ITO pattern visibility has not been investigated, and nothing is described on the application of the transfer materials in capacitance-type input devices.
In recent years, in order to solve the problem that transparent electrode patterns are visually recognized, a method of using a transparent laminate having a configuration in which a first transparent film, a transparent electrode pattern, a second transparent film, and a transparent protective film are laminated in this order, and the respective refractive indices of the layers are controlled to particular ranges, for capacitance-type input devices is known (see JP2014-10814A). In JP2014-10814A, the second transparent film and the transparent protective film are transferred in sequence using respectively different transfer films.